More 32X testing in the most recent BlastEm nightly - still got framerate problems, but Kolibri in particular kind of highlights where the problem seems to be coming from.
By disabling the (still very much scratchy-sounding) music in the game's options, the framerate jumped to a near-consistent 59~60 with only the occasional dip to 54, which means something in the emulator's sound-handling is likely what's causing the lag.

By disabling the (still very much scratchy-sounding) music in the game's options, the framerate jumped to a near-consistent 59~60 with only the occasional dip to 54, which means something in the emulator's sound-handling is likely what's causing the lag.

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